Cenozoic basalts are widely distributed in eastern China, and some of them contain zircon megacrysts which are considered to be constituent mineral of the subcontinental lithospheric mantle (SCLM) and petrogenetically related to mantle metasomatism induced by addition of crustal materials. Using the Laser Ablation Multiple Collector Inductively Coupled Plasma Mass Spectrometry (LA-MC-ICPMS), zircon megacrysts from the Cenozoic basalts at Changle in Shandong, Mingxi in Fujian, and Penglai in Hainan provinces have been used for Hf isotopic analyses. The data indicate that there is no significant deviation for the different zircon grains in each locale, except those from Penglai. The obtained 176 Hf / 177 Hf ratios are 0.28302 -0.28308 for Changle, 0.28297 -0.28300 for Mingxi, and 0.28288-0.28293 for Penglai, with corresponding ε Hf values of 8. 7-10.8, 7.0-7.9, and 3.9-5.7, respectively. These data display that there existed some regional heterogeneity, but the Hf model ages clustere in the Phanerozoic. Therefore, it is inferred that metasomatism of the lithospheric mantle beneath eastern China took place in the Phanerozoic, most probably in the Mesozoic-Cenozoic. However, the formation time of the lithospheric mantle is not clearly constrained based on the present Hf isotopic data.
As a kind of self-lubricating material, diamond-like carbon (DLC) film is famous for its excellent tribological properties. Superlubricity state with nearly-vanishing friction achieved with DLC film has enormous potential applications in future mechanical systems. It is pointed out that its superlubricity state is highly related to both the inherent properties of the DLC film and external sliding conditions. Moreover, the underlying mechanisms of the superlubricity are complicated, posing uncertainties on their engineering application. This review provides an overview of the influence factors, including film composition, ambient, temperature, normal load, and sliding velocity and their correlations with the anti-friction behaviors of DLC films. These understandings will enable a more effective engineering application of self-lubricating carbon films with excellent tribological properties.
Hydrogenated amorphous carbon (a-C:H) films are capable of providing excellent superlubricating properties, which have great potential serving as self-lubricating protective layer for mechanical systems in extreme working conditions. However, it is still a huge challenge to develop a-C:H films capable of achieving robust superlubricity state in vacuum. The main obstacle derives from the lack of knowledge on the influencing mechanism of deposition parameters on the films bonding structure and its relation to their self-lubrication performance. Aiming at finding the optimized deposition energy and revealing its influencing mechanism on superlubricity, a series of highly-hydrogenated a-C:H films were synthesized with appropriate ion energy, and systematic tribological experiments and structural characterization were conducted. The results highlight the pivotal role of ion energy on film composition, nanoclustering structure, and bonding state, which determine mechanical properties of highly-hydrogenated a-C:H films and surface passivation ability and hence their superlubricity performance in vacuum. The optimized superlubricity performance with the lowest friction coefficient of 0.006 coupled with the lowest wear rate emerges when the carbon ion energy is just beyond the penetration threshold of subplantation. The combined growth process of surface chemisorption and subsurface implantation is the key for a-C:H films to acquire stiff nanoclustering network and high volume of hydrogen incorporation, which enables a robust near-frictionless sliding surface. These findings can provide a guidance towards a more effective manipulation of self-lubricating a-C:H films for space application.
Clostridium butyricum, as a probiotic with a variety of active products, has been widely used to improve the intestinal health of humans and animals. Previous studies had demonstrated that Clostridium butyricum exhibited potential protective and positive effects in human disease research and animal production by producing a variety of beneficial substances, such as intestinal inflammation, the intestinal epithelial barrier, metabolic diseases, and regulation of the gut microbiota. Therefore, we hypothesized that dietary Clostridium butyricum supplementation could improve gut health in fattening goats by modulating gut microbiota. However, it is unclear whether Clostridium butyricum can reach the intestine through the rumen, so 15 healthy Albas goats were selected and randomly divided into 3 treatments with 5 replicates in each group. The groups were divided as follows: control group (CON: basal diet), rumen-protected Clostridium butyricum group (RPCB: basal diet plus 1.0 × 109 CFU/kg Clostridium butyricum coated with hydrogenated fat), and Clostridium butyricum group (CB: basal diet plus 1.0 × 109 CFU/kg Clostridium butyricum). The experiment was slaughtered after a 70-day growth test, and the jejunal mucosa and intestinal contents of the goats were collected to determine tight junction proteins related genes expression and 16S rDNA microbial sequencing analysis to evaluate the intestine health. The results showed that dietary supplementation with Clostridium butyricum significantly increased the expression of the Claudin-4 gene of the jejunal mucosa (P < 0.05) and had a trend toward a significant increase in the Occludin gene (0.05 < P < 0.10). However, Clostridium butyricum had no significant effect on the expression of intestinal inflammatory factors (P > 0.10). In addition, the relative fractionation of Clostridium and Clostridiaceae_unclassified in the gut microbiota at the genus level decreased significantly compared with controls (P < 0.05). The results of the analysis of the level of Clostridium species showed that Clostridium butyricum only existed in the treatment group. And the correlation results showed that Occludin and Claudin-4 genes were positively correlated with Sharppea and Clostridium butyricum, and negatively correlated with Clostridium (P < 0.05). Supplementing Clostridium butyricum in the diet did not significantly affect the intestinal immune function of goats, while regulation of the intestinal microbiota was associated with improving the intestinal epithelial barrier.
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